Measurements of traffic-related air pollution at a U.S.–Mexico port of entry and its impacts on nearby community

Traffic-related air pollutants are especially prevalent in border cities with multiple ports of entry (POEs). Excessive emissions due to long delays of idling commercial and passenger vehicles at the POEs could exacerbate various types of respiratory health conditions for the POE users and workers. We conducted a 1-month in-traffic air monitoring campaign at a POE in El Paso, Texas using three continuous FEM instruments for three criteria pollutants (PM, O3, and NO2). Concurrent monitoring of PM in the nearby community was performed using a number of low-cost PM sensors. The 1-month average PM2.5 concentration at the POE was found below 11.6 µg/m3, while the 5-min average of in-traffic PM2.5 concentration could be as high as 450 µg/m3. The in-traffic PM2.5 concentrations were comparable to the data concurrently measured in a state-operated community monitoring site approximately 0.4 km away from the POE. Ozone (O3) concentrations remained low in the region. The in-traffic 1-h NO2 concentrations were below the 1-h NAAQS of 100 ppb, except for only two 5-min intervals. Our results suggest that traffic emissions do not result in elevated levels of pollutant concentrations at this POE compared to the concentration levels observed in the nearby community. In addition, the performance and accuracy of the low-cost sensors appear to be less reliable during our study, although the devices were capable of detecting the trends and variability in pollutant concentrations in real time.